Plug assembly



May 11, 1954 c, w. ABBOTT PLUG ,ASSEMBLY Filed Dec. 29, 1950 X7@ L/40kATTORNEYS:

Patented May 11, 1954 PLUG ASSEMBLY Charles W. Abbott, Larchmont, N. Y.,assignor to Abbott Developments, Inc., New Haven, Conn., a corporationof Connecticut Application December 29, 1950, Serial No. 203,498

4 Claims. l

This invention relates to plug assemblies, of the type used with lampcords for insertion in wall receptacles and the like, as for example forconnecting lamps, toasters anda wide variety of electrical applianceswith a circuit wired to the receptacle.

Heretofore plug assemblies have been unduly bulky, not only protrudingfrom wall surfaces a considerable distance but holding cords connectedto them in a manner to cause further protrusion. For this reason .plugsare frequently broken, damaged or disconnected by being struck byfurniture, vacuum cleaners, brooms, floor mops and the like, or bytripping over their cords adjacent to them. Newer forms of plugs alsohave bases so narrow that they do not seat firmly against the surface ofreceptacle hubs into which they are thrust, hence their prongs areeasily partly or completely disengaged from receptacle contacts throughside movement imparted by strains on cords connected to them.

Furthermore, many :plugs require considerable skill and effort toconnect up conductors of lamp cords to their terminals, an a-ssemblythat makes necessary the use of knives, screw drivers and sometimespliers. Insulation must be cut or scraped off before conductors areconnected and both the strength and electrical carrying capacity ofconductors is often impaired by the cutting or breaking off of strandsin the process.

Unskilled bending of the wires around screw terminals results4 infailure to properly coniine short or str-ay strands of the conductorwhich sometimes result inshort circuiting, burning fingers of installersor setting .the cord insulation afire, When plugs so :wired are insertedin receptacles and current imposed on the conductors.

These diculties in wiring of Iplugs, are .to some degree lessened bynewer types of attachment plugs in which cord insulation is not removedbut is pierced by pointed contacts which supposedly make contact withconductors in the cords under external squeezing applied by variousmechanical means. However, the plugs f this type heretofore availablehave still been dimcult to assemble and are unsatisfactory becausefrequently the pointed contacts engage only a few strands of the manycomposing the conductor and often fail .to establish the low resistancecontact required to provide passage of permitted amperage withoutoverheating and loss` of electrical eiiiciency.

By the plug design, and assembly of component parts provided herein,bulkiness and protrusion of vplug and connected cord is reduced to aminimum heretofore thought impossible, and the task of assembly ordisassembly has been so simplified that it may be quickly and veryeasily done by unskilled persons without tools, and with complete anddependable safety. The tedious procedure of stripping off insulation and-properly assembling bare conductor ends beneath terminal screws iseliminated, and conductors may be assembled in the head of contactblades by slightly separating the two arms of the blade, inserting .theconductors in the yokes opposite spikes disposed to deeply penetrateinto the strands of conductors, pushing the prongs of the contact bladesinto the accurately dimensioned slots in the -plug body, and screwingthe cover of the .plug in vplace to Afirmly lock the conductor assemblyin place.

An object of the invention is to provide a simple, 4practical anddurable plug assembly.

Another object of the invention is to provide in a plug lassemblycontact blades of improved structure adapted to receive and provide goodconta-ct with new or worn cords.

Another object of the invention is to provide a plug occupying a minimumof space, which may be assembled or disassembled without tools, and inwhich a pointed contact is moved into accurate, low resistance contactwith the conductive core of a cord by the simple act of inserting acontact prong in a plug body.

Other objects of the invention will be in part obvious or in partpointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements, arrangements of parts, and in the severalsteps and relation and order of each of said steps to one or more of theothers thereof, all as will be pointed out in the following description,and the scope of the application of which will be indicated in thefollowing claims.

The invention will best be understood if the following description isread in connection with the drawings, in which,

Figure 1 is a yperspective view of a plug assembly embodying myinvention, looking at lthe top of the cap;

Figure 2 is a perspective View of the assembly shown in Figure 1,looking at the face of the plug which in use is against the receptacle,and which is referred to herein as the under face;

Figure 3 is a side elevational view of the assembly shown in Figures 1and 2; Figure 4 is a top plan view of the plug body with contact bladesand .conductor ends positioned in the channels and recesses provided inthe face of the plug `which is adjacent the cap and which is referred toherein as the inner face;

Figure 5 is a view similar to Figure 4 but partly in cross section;

Figure 6 is a cross sectional view, showing the cap in exploded relationto the plug body with one Contact blade seated in tlieplug` body andengaging a conductor end therein, the section of the plug body beingtaken on the line S-' ofV Figure 4;

Figure '7 is a detail view on a large scale siniA ilar to Figure 6 butshowing the cap assembled'to the plug body and clampingheheadofacontact:

blade between itself and the Aplug body; 'Y

Figure Sis a perspective View showing the con-- 25' and the lugs $3,732and the ribbed ystructure of the spike'and ofthe contact blade arm.

Theassembly described herein comprises only four parts,V namely,arplugbodyV it, two separate and removable contactbladesl2 which areidentical, and a cap` ille if the cap is made of metal, instead or"insulating'material, and a-layer of insulating material I is supplied onthe inner surface of the cap, as shown herein, the total nurnber ofdifferent partsernployedfor the Whole assembly are five in number, andif thecap screw i8 is formedinitially separate from thecap, Aand laterjoined to the'cap, the. total number of parts required' may be said tobe six.

Essentially there areonly three-parts, the plugV body, thecontactblades, and cap, and these may be readily assembledfor. disassembled atany time. No separaterscrews orjbinding posts are employed. Thecontactblades lZvare not molded Vinto the plug body it, the insulation need notbe removed from the conductor ends, and no effort Yis required foreffecting electricalcontact between a blade `and a conductor otherlthan; toV position the conductor end in aV conductor.receivin-grportionof the vbladefand insert lthe blade in theopening in the plug:bodyprovidedxfor this purpose Y tact blades in exploded relationtotheplug. body,

receiving portion 23 and establish electrical contact with the core 29of the conductor.

Projecting from arm 22 on either side of spike 2t lugs 39 and 32 areprovided bent substantially at right angles to said arm 22 but in adirection substantially opposite to the spike 26.

Preferably spike 2e is ribbed along its median line, as at'3fl; arm 22isribbed'intermediate its ends, as at 35j and arm 2li-is ribbed, as at38, to give greater strength and accurate spacing to said members. Y`In. the plug body It channels l@ and 42 are provided, preferably bymolding them in the outer Vfacefofthe plug; These channels have theirbeginning inLajcomni-on opening 44 provided in the ofthepartition ordividing wall 45, and then exand are undercut between them .0301` Y Thetops of theribs are shownslightly, rounded.

In the parallel portions. of4 channels Il and'. 42 recesses #33 and 59,are, provided which receive the conductor receiving'hportions QS-ofl thecontact of` saidconductor receivingportions 28'.V shoulders coact withsaidfrecesses respectively to blades i2, referred to herein also.,Y as,angle or bracket portions, and in said recesses ,.tliejopenings :it and5d. areprovided which-.extendthrough the wall oiY thev plug',- andthroughY which the prongs ofthe contact blades are inserted'inTassembling the blades andl the plug body. Y

Along the outer margins, ofjsaidY openings 52 and eli respectively,shoulderstand' areprovided, rising ahovesaid'cliannels eiland 42; by anamount substantially equal'to, one half' the height Said position theheads oil the contactblades respecu tively including the conductorreceiving portions E8 thereof," and'also serve as seats, on .which restsaidlugs 3i) and S2; which in turn aidin holding the contact blade arms,22leveland'rmly seated in .the plug base. hugs .'i'and''coact with saidshoulders andY said recesses .to provide stops limit'- ing theinsertionof' the blades through the. openwardly adjacent its upper end. ItVisshown herein as substantially L15-shaped, providing achannel in whicha conductor end may be rested andlposi; tioned, said channel being openin the direction i of the spike 26, adjacenty the free' end of'garm 22;so

ings 52jand ll'randin providing surfaces between which andthe capY theheadsv ofthe blades are iirrnlylield when the'cap; lfis secured onan'dover theplugbody.

The openings 52and Eilare preferably justllarge enough torreceive theblades 'l2-With' their' arms 22"*and 276isubstantiallyA parallel;Consequently when a blade is inserted inoneofsaidopeningsthebent-orffolded errdvv'illl enter the openingr read-ily andthe sidesof the-opening will force the arms 2? and to^ approachone another'Vwith'thegresultmthat byY the tinietheconductorreceiving-portionorfbracket''is seated'in recess the covering of;Aandinto' Contact with the core Y th'epartitioniltl and"extending'f rom'the inner face of the plugbody toward the reargface of 4:the

vplug body, ,and-"capi `l A; hasjprojectin'gi fromfthe Y center of itsinner surface the screw I8, which as stated above, is integral with capI4, and is adapted to be received in and threadedly engaged in the saidbore 8|] of the body. Since the cap I4 may be easily grasped by hand andturned it may be readily assembled to or disassembled from the plugbody, without the use of tools of any kind. For convenience the downturned peripheral flange I5 of the cap may be knurled as shown in Figure3.

Whenthe cap is secured on and over the plug body its insulated innersurface I6 coacts with the inner face of the plug body in holding thecontact blades seated in the plug assembly with their prong portionsprojecting the desired distance externally of the plug body.

The assembly of the plug body and cap has a thickness of onlyapproximately one-fourth of an inch. `lli/'hen inserted in a Wallassembly it lies close to the wall and is not likely to be dislodgedinadvertently as by being struck by floor mops, polishers, or byfurniture which is being moved. If desired the plug assembly may bequickly and easily disassembled and detached from one set of conductorsand attached to another set of conductors and reassembled, without theuse of any tools and the conductor ends are held at all times so as tomake short circuiting practically impossible.

It will thus be seen that there has been provided by this invention anarticle in which the various objects hereinabove set forth together withmany thoroughly practical advantages are successfully achieved. Asvarious possible embodiments might be made of the mechanical fea-` turesof the above invention and as the art herein described might be variedin various parts, all without departing from the scope of the invention,itis to be understood that all matter hereinbefore set forth or shown inthe accompanying drawing is to be interpreted as illustrative and not ina limiting sense.

What I claim is:

1. A contact blade for use in a lamp cord plug comprising a length ofconductive metal folded to provide two slightly diverging arms one ofsaid arms comprising adjacent its free end a U -shaped channel havingits axis substantially lperpendicular to said arm and being open in thedirection of the other arm but extending around a conductor thereinthrough at least said other arm comprising adjacent its free end a spikeprojecting toward the center of said U-shaped channel.

2. A Contact blade for use in a lamp cord plug comprising a length ofconductive metal folded to provide two slightly diverging arms one ofsaid arms being bent adjacent its free end into a U-shaped channelhaving its axis substantially perpendicular to said arm and open in thedirection of the other arm to receive and retain a conductor therein,said other arm having its end terminating in a spike bent over at rightangles to said arm and projecting toward the center of said U-shapedchannel.

3. The device as claimed in claim 2 in which said blade is embossedthroughout a portion of its length to provide a strengthening ribincluding at least the portion of said blade comprising said spike.

4. The device claimed in claim 2 including lug means projectingsubstantially at right angles from said other arm adjacent its free end,and having a bear-ing surface extending from the arm in a directionopposite to said spike.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,956,018 Gilbert Apr. 24, 1934 2,112,752 Abbott Mar. 29, 19382,145,596 Grant Jan. 31, 1939 2,309,311 Grohsgal Jan.. 26, 19432,475,243 Irrgang July 5, 1949 2,564,159 Greacen Aug. 14, 1951

